Spinal surgeries to correct causes of back pain and injury have steadily increased over the past several years. Arthrodesis of the vertebrae, otherwise known as spinal fusion, has become a recognized surgical procedure for spine surgeons to treat fractured vertebrae, disc herniations, deformities, and other spinal problems. Spinal fusion surgery typically includes immobilizing one or more vertebrae by plates, screws, cages, or other implantable fixation devices. Depending on the type of surgery and location of vertebrae fusion, entry point incisions can be made from the posterior (back) or anterior (front) of the patient along the cervical (neck), thoracic (chest), or lumbar (lower back) regions.
In the case of posterior spinal surgery, spinal fusion operation is complicated by the fact that major blood vessels lie to either side of the operative area. In addition, the spinal cord, nerves, and other tissues encased or surrounding the vertebrae are particularly exposed. Extreme care and precision are required to prevent damage of vital tissues during spinal surgery and vertebrae fusion.
Spinal implant devices currently used for spinal fusion, especially in the C1 cervical spine near the base of the skull, lack the ability to remove fixing devices, such as pedicle screws, without excessive side to side loosening. In the C1 cervical spine, where there are sensitive tissues and complex bone structure, when an inserted instrument becomes jammed, lateral movement or force will tend to damage the surrounding area. In addition, screws that are threaded into a vertebrae at an angle with respect to an opening may damage sensitive tissues such as arteries and nerves in the back of the neck. The surgeon's lack of control over screw exit angle, as well as entry angle, is a problem in performing this type of cervical spinal fusion procedure. Even further, during cervical spinal surgery the surgical field is often obstructed, and complicated instruments can block a significant view of the surgical site. Although many developments have been made in the art of surgical devices for spinal surgery, further improvements are needed to reduce the visual and manual obstruction in the surgical field.